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Test Code GLP Glucagon, Plasma

Important Note

  • Must be drawn at Outpatient Lab at the Main Campus
  • Must be Fasting
  • Collect in Pre Chilled Lavender Tube
  • SEND ON ICE

Reporting Name

Glucagon, P

Useful For

Diagnosis and follow-up of glucagonomas and other glucagon-producing tumors

 

Assessing diabetic patients with problematic hyper- or hypoglycemic episodes (extremely limited utility)

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Plasma EDTA


Specimen Required


Patient Preparation: Fasting (8 hours)

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube: Lavender top (EDTA)

Submission Container/Tube: Plastic vial

Specimen Volume: 2 mL

Collection Instructions:

1. Pre-chill lavender top (EDTA) tube at 4° C before drawing the specimen.

2. Draw blood into the pre-chilled tube and process as follows:

 a. Chill filled tube in wet ice for 10 minutes.

 b. Centrifuge in a refrigerated centrifuge or in a pre-chilled centrifuge carrier.

 c. Immediately after centrifugation, aliquot plasma into a plastic vial and freeze.


Specimen Minimum Volume

0.45 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma EDTA Frozen 90 days

Reference Values

≤6 hours: 100-650 pg/mL

1-2 days: 70-450 pg/mL

2-4 days: 100-650 pg/mL

4-14 days: declining gradually to adult levels

>14 days: ≤80 pg/mL (range based on 95% confidence limits)

 

Glucagon levels are inversely related to blood glucose levels at all ages. This is particularly pronounced at birth and shortly thereafter, until regular feeding patterns are established. This explains the higher levels immediately after birth, which then first fall as the glucagon release mobilizes the infant's glucose stores, then rise again as stores are depleted, finally normalizing towards adult levels as regular feeding patterns are established.

 

For International System of Units (SI) for Reference Values, see www.mayocliniclabs.com/order-tests/si-unit-conversion.html.

Day(s) Performed

Tuesday, Thursday

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

82943

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GLP Glucagon, P 2338-2

 

Result ID Test Result Name Result LOINC Value
9358 Glucagon, P 2338-2

Interpretation

Elevated glucagon levels in the absence of hypoglycemia may indicate the presence of a glucagon-secreting tumor. Successful treatment of a glucagon-secreting tumor is associated with normalization of glucagon levels.

 

Inappropriate elevations in glucagon levels in hyperglycemic type I diabetic patients indicate that paradoxical glucagon release may contribute to disease severity. This can be observed if insulin treatment is inadequate, and patients are ketotic. However, glucagon measurement plays little, if any, role in the diagnostic workup of diabetic ketoacidosis, which is based on demonstrating significantly elevated plasma or serum glucose (>250 mg/dL), circulating ketones (beta-hydroxy butyrate), and acidosis (typically with increased anion gap).

 

In diabetic patients, low glucagon levels (undetectable or in the lower quartile of the normal range) in the presence of hypoglycemia indicate impairment of hypoglycemic counterregulation. These patients may be particularly prone to recurrent hypoglycemia. This can be a permanent problem due to islet alpha-cell destruction or other, less well understood processes (eg, autonomous neuropathy). It can also be functional, most often due to over-tight blood glucose control and may be reversible after decreasing insulin doses.

Clinical Reference

1. Tomassetti P, Migliori M, Lalli S, Campana D, Tomassetti V, Corinaldesi R. Epidemiology, clinical features and diagnosis of gastroenteropancreatic endocrine tumours. Ann Oncol. 2001;12 Suppl 2:S95-99

2. Jhiang G, Zhang BB. Glucagon and regulation of glucose metabolism. Am J Physiol Endocrinol Metab. 2003 Apr;284(4):E671-E678

3. van Beek AP, de Haas ERM, van Vloten WA, Lips CJM, Roijers JFM, Canninga-van Dijk MR. The glucagonoma syndrome and necrolytic migratory erythema: a clinical review. Eur J Endocrinol. 2004;151(5):531-537

4. Cruz-Bautista I, Lerman I, Perez-Enriquez B, et al. Diagnostic challenge of glucagonoma: case report and literature review. Endocr Pract. 2006;12(4):422-426

5. Falconi M, Eriksson B, Kaltsas G, et al. ENETS Consensus guidelines update for the management of patients with functional pancreatic neuroendocrine tumors and non-functional pancreatic neuroendocrine tumors. Neuroendocrinology. 2016;103(2):153-171

Report Available

3 to 7 days

Method Name

Immunoassay

Forms

If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.